1. Field of the Invention
The present invention relates to the testing of induction motors and, more particularly, to a method for routine inspection of every motor produced.
2. Description of the Prior Art
Single-phase induction motors of fractional horsepower size, such as are used in appliances, are produced in large volume by assembly line methods. Because of this large production volume which, in many cases, may run into thousands of motors per day, it has not heretofore been practical to comprehensively inspect all motors produced; that is, to make tests of all the motor characteristics which it would be desirable to determine. A relatively few simple checks, such as no-load power and current, and insulation integrity, have been made, but these do not directly yield any information concerning motor torque characteristics, friction or bearing losses, and other desirable quantities. Complete tests for quality control purposes have been made heretofore, but on only a relatively few motors selected at random. The great majority of motors produced have thus not been comprehensively tested. Inspection of all motors including tests for torque characteristics and bearing tightness or friction would be highly desirable and would tend to improve the quality and reliability of the end product. This has not heretofore been possible, however, because of the time required and the cost involved in inspection by conventional methods of all motors produced.